Mechanical dyssynchrony and contractile function measured with speckle tracking predicted benefit from CRT in terms of reduced risk of death or heart failure events, Scott D. Solomon, of Brigham and Women's Hospital in Boston, and colleagues found in a subanalysis of the MADIT-CRT trial.

Each one percentage point improvement in baseline left ventricular contractility predicted a 27% advantage for these outcomes with CRT in the trial after full multivariate adjustment (P<0.001), the group reported here at the European Society of Cardiology's Heart Failure Congress.

The results were published online in Circulation: Heart Failure and the European Heart Journal in two separate papers after the presentation.

Each 20 millisecond decrease in baseline left ventricular dyssynchrony was associated with a 7% adjusted benefit for the primary outcome of the trial with CRT (P=0.047), although the measure lost significance with full multivariate adjustment (P=0.17).

"These methods are more robust and reproducible than earlier Doppler techniques and may help to identify which patients would derive greater benefit from CRT," Solomon said at the late-breaking clinical trials session at which the data were presented.

However, these techniques may not actually work out that well as clinical tools in everyday practice, cautioned session co-chair Stefan Anker, MD, PhD, of the Charité Campus Virchow-Klinikum in Berlin.

"These results I look at as telling us something about the pathophysiology and biology more than pointing to whether or not a specific technology should be used by individual laboratories," Solomon responded at the session.

He noted that the technologies are likely to become more automated in the future but agreed that, until tested prospectively, the techniques should not be used to decide which patients should or should not get CRT.

Such techniques might have a role in identifying CRT candidates with borderline QRS and preserved ejection fraction, but a multivariate approach is likely to be better than a single "magic echo-bullet," noted study discussant Frieder Braunschweig, MD, PhD, of the Karolinska University Hospital in Stockholm.

MADIT-CRT randomized 1,820 patients with mild New York Heart Association class I or II heart failure to a cardiac resynchronization plus cardioverter defibrillation (CRT-D) device or to an implantable cardioverter-defibrillator (ICD) alone.

The main trial results had shown a 34% advantage to CRT-D for the primary endpoint of heart failure events or death.

The analysis Solomon reported included 761 patients with paired imaging studies at baseline and 12 months with 2D speckle-tracking echocardiography.

This imaging generated measures of dyssynchrony (time to peak radial or transverse strain) and contractile function (the average of longitudinal strain).

Poorer contractility appeared significantly associated with the risk of death or heart failure events in both CRT and ICD treated patients, although more so for CRT (HR per 1% increase in strain 1.19 and 1.09, respectively).

Baseline dyssynchrony wasn't significantly linked to outcomes with ICDs alone but did have a U-shaped relationship to CRT-D outcomes, with a "clear inverse relationship" at the lower quartiles of dyssynchrony, Solomon told attendees.

Improvements in synchrony and in contractility were greater with CRT-D than with ICDs (both P<0.001).

Limitations of the study included that patients with poor quality or nondigital images were excluded and fewer patients had follow-up studies with the device on than at baseline, Solomon noted.

The MADIT-CRT trial was funded by a grant to the University of Rochester from Boston Scientific.

Solomon reported receiving consulting fees from Boston Scientific.

Anker has reported being a consultant for Robert-Bosch Healthcare, Thermo Fisher Scientific Germany and St. Jude Medical and receiving honoraria for speaking from Thermo Fisher Scientific Germany and St. Jude Medical.

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